The present invention relates to the transport of freight by railroad using a rail car with a rotatable loading floor pivotally mounted to it for the quick loading and unloading of vehicles which can be rolled onto and off of the loading floor from a station platform located adjacent the side of the rail car and, more particularly, to structure for securing the rotatable loading floor in its stowed position during travel which stiffens the rail car for heavy loads and buffers the loading floor against horizontal movement in the longitudinal direction.
Various approaches have been utilized to facilitate the transfer of loads, such as vehicles, between rail cars and station platforms. As disclosed in U.S. Pat. No. 4,425,064 a rotatable loading floor is pivotally mounted onto the chassis of a rail car. When a train of such rail cars travels between stations, the loading floor is stowed with its longitudinal axis being aligned with the longitudinal axis of the rail car chassis. When the train arrives at a station platform, the rotatable loading floor is pivoted so that at least one of its ends rests on a station platform. Loads can then be transferred between the loading floor and station platform by, for example, rolling them, as with or on a vehicle.
When the train is in motion between stations, it is important to lock the rotatable loading floor in its stowed position. Otherwise, the jostling which occurs as a result of acceleration, deceleration, and rocking motion imparted by the tracks may cause the loading floor to swing outward. Serious damage and injury could then result.
To prevent this from happening, U.S. Pat. No. 4,425,064 discloses a locking pin secured to the chassis at either end of the loading floor and centered in the transverse direction. The locking pins fit into suitably sized openings in the loading floor. However, a strong car buffer is preferred to act against horizontal motion of the loading floor in the longitudinal direction. Also, heavy loads tend to cause the chassis to sag. The pin arrangement of this patent does not adequately "stiffen" the chassis to minimize this sag.
U.S. Pat. No. 3,916,799 discloses securing pins which slide vertically within openings in the loading platform. Sockets in the chassis are sized to receive these pins when the loading floor is in its stowed position. This arrangement is, however, deficient in adequately performing the "buffering" and "stiffening" functions mentioned above.
Another difficulty associated with prior art rail cars involves the motorized rotating means used to swing the loading floor to its operative position on the station platform. Various gearing mechanisms have been used to couple the motors to the loading floor. However, due to the arrangement used in these approaches, less than the optimal torque has been applied resulting in the inability to rotate the loading floor if it carries very heavy loads.